Introduction: Atrial fibrillation (AF) is a common finding in patients presenting with myocardial infarction (MI). Despite the high incidence of AF, ranging between 5-20%, its
prognostic implications are controversial, particularly in the primary percutaneous coronary intervention (PCI) era.
Methods: We analyzed data from our prospective registry of 1334 consecutive patients hospitalized for STEMI in our intensive cardiac care unit. Patient records were reviewed
for the presence of AF, its time of occurrence and relation to in-hospital complications as well as long term mortality over a 5 year period.
Results: Mean follow up time was 1058 days. Atrial fibrillation was documented in 117 cases (8.7%), of whom 47 cases (3.5%) had a prior diagnosis of AF and 70 cases (5.2%)
had a new onset of AF (NOAF). The occurrence of AF during hospitalization resulted in a significant increase in 30-day (3.4% vs. 2.1%, P<0.05), 1 year (7.7% vs.
3.5%, P<0.05) and long-term (25.6% vs. 9%, P<0.05) mortality throughout the follow-up period of 2500 days (figure 1). This excess risk was independent of difference
in known adverse prognostic factors in AF such as represented in the CHADS2 score. Surprisingly, there was no difference in mortality between patients with prior
documented AF and patients with NOAF.
Conclusions: The occurrence of atrial fibrillation is a significant adverse prognostic factor in patients with STEMI, regardless of its timing of presentation. Our finding may call for incorporation of AF into traditional risk stratification models of MI.
